1. Field of the Invention
The present invention generally relates to a data transferring system, and more particularly to a system and method for transferring data using a universal serial bus (USB).
2. Background of the Related Art
In order to transfer data from a mobile terminal to a computer, a cable has been used to connect a data port of the terminal to a USB port of the computer. The computer receives the data stored in the terminal by performing programs for driving transfer of the data.
FIG. 1 shows a system for transferring data between a mobile terminal and computer in accordance with the related art. The system comprises a terminal 1 containing a data port, a cable 2 for connecting the terminal to a computer, and a computer 3 having a USB port and a program for receiving data stored in the terminal through the cable. The USB cable is composed of a VBUS line for supplying a power, a D+ line and a D− line for transmitting and receiving data, and a ground line (GND).
A data transfer process between the terminal and computer will now be explained. First, the USB cable is connected at one end to the data port at terminal 1 and the USB port of the computer 3 at the other end. The computer 3 executes a program (such as PC sync) for initiating transfer of the data stored in the terminal through the USB cable. If data is transmitted from the terminal, the computer receives the data by operating a USB reception thread (Rx Thread).
When the computer executes a data receiving program and the terminal transmits data to the computer through the USB cable, data input time from the terminal to the computer cannot be predicted. Even if there is data to be transmitted to the computer from the terminal, if the USB reception thread of the computer is not operated, the computer cannot receive data. That is, the computer has to certify whether data to be transmitted from the terminal exists by frequently operating a reception register. If there is data to be transmitted from the terminal, the computer has to continuously and speedily operate the USB reception thread for storing the data in a temporal buffer in order to receive the data.
The thread has a performance time which corresponds to the manner in which time is divided under a control of a kernel. The thread also has a priority and is scheduled by the priority to be performed. Therefore, if the USB reception thread is continuously performed with high priority, threads of other programs performed in the computer have less performance time. As a result, the performance speed of other programs including threads, except the USB reception thread, becomes low therein causing abnormal operation and further causing a problem in system stabilization such as a computer down malfunction.